Many file cabinets open to such an extent and hold such heavy material as to tend to and actually do tip over forwardly if more than a single drawer is open. This tilting may be injurious to the person and it is very desirable to avoid it. Interlocks have been suggested in the past, see U.S. Pat. Nos. 4,429,930, Feb. 7, 1984; 4,303,287, Dec. 1, 1981; and 4,298,236, Nov. 3, 1981 as examples of this art; but all prior such devices are not completely satisfactory as to operation, cost, and even noise, and an improved interlock device is presented in this case that is easier to install and smoother in operation, more positive in action. Other advantages will become more clear hereinafter.